Boston-based private-equity firm Berkshire Partners and OMERS Private Equity of Toronto reportedly paid $2.1 billion last month to jointly buy Husky International Ltd. and its subsidiaries, which makes injection molding machines, hot runners and molds. Husky was founded in 1953 by Robert Schad, who sold the company to Onex Corp. in 2007. Husky’s operating profit reportedly more than doubled since then. The transaction is expected to close by the end of the third quarter.